Rotating or swinging radar systems may have both primary and secondary radar devices which produce radiation lobes along the same axis. The result is that after the primary device has made contact with the target by receiving the target echo, it is no longer possible to send interrogation signals by the secondary radar device until the system has made another pass at the target. In the case of a rotating device this means a complete 360.degree. additional revolution. Because of such systems, the load on the radar facility can become excessive. According to the present invention, contact by the secondary radar device is made immediately following receipt of the target echo by the primary radar device, thereby eliminating the load on the radar system.